Earlier quoted context omitted.
Neither PHP nor Python have anything approaching CPAN. Ruby is slightly closer with Gems, but even that's a joke compared to the might of Perl libraries. Seriously, that's the big thing that's missing. Other than that both PHP and Python are prefectly servicable, although you're going to have an easier time finding smart Python developers than smart PHP developers (Blub hiring paradox).
And perl has nothing approaching Python's readability. Perl may be easier to start with now but in 6 months, it will become a major headache. Read http://www.linuxjournal.com/article/3882 . Using Python would be an excellent choice imo.
$ for scalars (single values without dimension)
@ for arrays
% for hashes (like python's dictionaries)
With python, you have to guess.
Of course, many people who are intimidated by Perl have made the same statement about readability, and it is often repeated unthinkingly. That doesn't mean it's true.
On the other hand, Perl does make it easier to write unreadable code. Just like any powerful tool -- cars, telephones -- it can be abused.
All that being said, I think Python is a great choice too; I just disagreed on the readability point.